The evidence for the presence of estrogen and progesterone receptors in the human prostate has been conflicting. Some of the methodological problems related to the measurement estrogen receptors in the prostate have been solved previously in our laboratory by using 16 Alpha125 Iodo-Estradiol as a ligand and an HPLC column to isolate proteins compatible with the receptor. This method has enabled us to process small sample size specimens and therefore, use effectively needle biopsies from prostate tissue. Evidence has accumulated by a large majority of specimens studies that carcinoma of the prostate with few exceptions have very low levels of estrogen receptors. Benign prostatic hyperplasia has shown consistently to have estrogen receptors in higher quantities than carcinoma. The presence of a progesterone receptor in human prostate has been suggested by recent work done at our laboratory. Because of the relationship of estrogen and progesterone receptor in breast cancer and because of recent clinical evidence of prostatic carcinoma response to anti estrogen and progestational agents, it is important to define the presence and the relationship of estrogen and progesterone receptors in prostatic cancer. We propose to study the presence of both estrogen and progesterone receptors in prostatic carcinoma patients and to relate the findings to the clincal response to anti estrogen or to progestational agents.